论文标题
Moiré表面状态和拓扑绝缘体的超导性增强
Moiré surface states and enhanced superconductivity in topological insulators
论文作者
论文摘要
最近，由于最上层的旋转不对，在拓扑绝缘子（TI）的表面上发现了Moiré超晶格。在这项工作中，我们使用狄拉克电子的连续模型在周期性的潜力中研究Moiré超级晶格对拓扑表面状态的影响。与扭曲的双层石墨烯不同，莫伊尔的表面状态由于其拓扑性质而无法容纳孤立的带。取而代之的是，我们在Moiré带结构中发现（高阶）Van Hove奇异性（VHS）产生了态度不同的状态密度（DOS）并增强相互作用的效果。由于莫伊尔表面状态下的自旋摩托明锁，可能的相互作用通道受到限制。在存在声子介导的吸引力的情况下，高阶VHS处的幂律DOS强烈增强了超导性。过渡温度$ t_c $表现出对智障电子相互作用强度$λ^*$的幂律依赖。在高阶VHS的各种扰动下，发现这种增强功能是鲁棒的。
Recently, moiré superlattices have been found on the surface of topological insulators (TI) due to the rotational misalignment of topmost layers. In this work, we study the effects of moiré superlattices on the topological surface states using a continuum model of Dirac electrons moving in a periodic potential. Unlike twisted bilayer graphene, moiré surface states cannot host isolated bands due to their topological nature. Instead, we find (high-order) van Hove singularities (VHS) in the moiré band structure that give rise to divergent density of states (DOS) and enhance interaction effects. Due to spin-momentum locking in moiré surface states, possible interaction channels are limited. In the presence of phonon mediated attraction, superconductivity is strongly enhanced by the power-law divergent DOS at high-order VHS. The transition temperature $T_c$ exhibits a power-law dependence on the retarded electron-phonon interaction strength $λ^*$. This enhancement is found to be robust under various perturbations from the high-order VHS.
